1899] ORIGIN OF A USTRALIAN FLORA 2 1 1 



in which, for instance, Galinsoga parviflora, and species of Aster are 

 enabled to maintain themselves in Europe, any inherent superiority of 

 the American flora over the European ? Yet argument of this kind we 

 find constantly applied to the flora of Australia. Nor is present dis- 

 tribution an infallible index to the place of origin of a genus or 

 species. To take two instances showing the general trend of argument 

 on this subject as bearing on the flora of Australia : Hclichysum and 

 Hdiptcrum, although well represented in Australia, are found also in 

 other countries ; consequently, it is said, they are exotic genera which 

 have at some time migrated into Australia. Why may not they, as 

 well as other genera, be descendants from the constituents of the 

 " primitive tertiary flora " ? Professor Tate partially adopts this view, 

 for he remarks, apropos of certain genera found fossil in tertiary 

 deposits, such as Ficus, Loranthus, Pittosporum, Santalum, and Cassia — 

 that most of these genera, " when viewed by their present geographical 

 distribution, are considered Oriental ; but in regard to their distribution 

 in time they belong to a cosmopolitan flora, which originated in late 

 Cretaceous times in Europe, North America, and Australia ; hence their 

 modern representatives may actually be descendants of primitive 

 Australian species, and not modified immigrant forms." 1 But though 

 he makes this highly important admission, in practice he adopts the 

 conventional view, for we find him distinguishing "immigrant" genera 

 and species from " endemic " ones with confidence as serene as though 

 he had himself been privileged to watch, through long ages, all the 

 various steps in the stocking of Australia. Of course the view I am 

 advocating cuts both ways. The Cambodian Centrolcpis, for instance, 

 may possibly be the sole Indo-Malayan survivor of a genus which had 

 its origin in the Indo-Malayan region, and migrated thence into 

 Australia. So too Patcrsonia may be of Indo-Malayan origin : even 

 Casuarina equisctifolia may be, for all we know, the original species 

 from which its Australian congeners have been derived. Not until all 

 later secondary and tertiary deposits have been thoroughly ransacked, 

 and their respective relations in time established beyond dispute, will 

 it be possible to fix upon that part of the earth where a genus or a 

 species first made its appearance. Until this is accomplished our con- 

 clusions can rest on nothing more satisfactory than inferences from 

 present distribution, which, unless they be applied with the utmost 

 caution, may lead us far from the truth. 



The most recent and, as having been deduced with full knowledge 

 of modern geological discoveries and after personal inspection of part 

 of the country, the most authoritative conclusions relative to the origin 

 of the Australian flora are those of Professor Tate. 2 The Darling 



1 "Botany of the Horn Expedition," p. 131. 



- Professor Tate's three memoirs, The Influence of Physiographic Changes in the Dis- 

 tribution of Life in Australia; Australia's Association for the Advancement of Science 

 (1887) ; Inaugural Address, in the Association's volume for 1893, and the " Botany of the 

 Horn Expedition " (1896), are most interesting contributions to the subject under notice. 



